Arda Guler stayed on the pitch against Sevilla, and the fallout was immediate. The Andalusian side's players accused the Turk of catching Peque Fernandez with his elbow, yet the video assistant referee never called the official over to the monitor to take a look.
Sevilla defender Kike Salas aired his frustration to "Movistar" at half-time, backing his team-mate's version of events despite not having seen a clear replay himself at that stage.
Salas said: "I think we were in control of the match until Guler's goal, even though before that he struck Peque with his elbow, which I consider an offence that warrants a clear red card. He told me that he struck him with his elbow clearly, and I trust him. I'm going to watch the replay now, but I don't know why the video assistant referee did not intervene, even just to review the incident."
It all traced back to the 22nd minute. Peque tried to halt a Real Madrid counter-attack and went down after a movement of Guler's arm, and Sevilla's players swarmed referee Busquets Ferrer, demanding a red card for what they saw as violent conduct.
The VAR room did look at it. What they found was not conclusive enough to send the referee to the screen, with the replays failing to show the point of contact precisely or establish the force of the blow. Guler stayed on without a card. The protests that followed earned Huijsen and Felix Correa yellows.
Eight minutes later, the Turk made it worse for Sevilla. Guler struck a superb finish after a decisive pass from Diomande, putting the Royal side ahead in a game that had already featured a running argument between the visitors and the officials.
Kylian Mbappe then doubled the lead a few minutes after that, finishing off a brilliant piece of individual play. Sevilla were left insisting that a red card for Guler would have changed the whole shape of the afternoon.